Friday, May 18, 2012

Home-made 4WD rooftop awning

This article describes how to build your own rooftop awning. I recommend that if you do want an awning, purchase one from a store. They have come down in price considerably since I built mine.
If you do go ahead, make sure to check with your local transportation authority and check whether such a device is legal in your country/state.

Anyway, let's start. A while ago I wanted a rooftop awning but I didn't want to pay that much money. In Australia, these awnings go for several hundred dollars, and the small ones are indeed quite small. So I built my own, instructions are below. This is how it looks like:

Most of the stuff I got from Bunnings, the poles from the camping store and the velcro from a textile store next to the BCF at Cannon Hill.

The basic design is simple. The tarp is held onto the square tube by a bunch of vertical bolts - one per tarp eyelet. The crossbar, which is too long for my tray, is held in place by two horizontal bolts, on the inside (towards the car). The tarp is folded in half, then rolled up and held in place by three strips of velcro.

Tarp when rolled up for transport.

I have Rhino Rack Aero bars and the bolts I got had a head exactly the size of the groove. So I don't need mountings, I simply push the screw into the groove, then sit the awning on it and tighten the nut up the top. And, second time lucky, the eyelets are the distance of my roof racks, so I don't have to do anything there either.

The bolt fits exactly into the groove - lucky me :) Obscured by the rolled-up tarp is the top end of the bolt - simply a washer and a nut.

Assembly instructions

Drill a hole a few cm in from one ond of the square tube. Now take a bolt and nut, screw the tarp's corner to the tube. Stretch it to the other end, drill another hole, bolt, nut, done. The tarp should be tightly stretched. Now mark each eyelets in the middle for more holes. Take the tarp off, drill the remaining holes, then saw the excess square tube off.

Bolt shown from the side

As said above, my roof racks are exactly the distance of the eyelets, so I don't need extra mountings. The professional awnings have an L-shaped attachment that goes into the roof racks and the awning then hangs off the side. This photo shows the attachment, the same should be possible on this home-made model.

The final bit are two horizontal drillings through the tube. They are for mounting the crossbar next to the tube. I transport the four poles, the ropes and the pegs in the tray.

Crossbar mount. The bolt is horizontal when mounted.

The front bit of the rolled-up awning, taken from the other side of the car, showing the crossbar mount.

Setting it up is simple enough, though it does require 2 people. It takes a few minutes to set up, a few minutes to pack up again. If the tarp gives up, I can (hopefully) buy another one and replace it.

Costs for me was just over AUD 100, including the crossbar and the poles. If you already have those, you're obviously able to build it for much less.

Side notes

As I have the handyman's knowledge of a five-year-old, I did a few things wrong. First,
Bunnings sells bolts in imperial and metric. Had I known that, I'd have bought metric screws. I ended up just getting the first set that matched the size I needed. The metric section was a few metres further down the aisle.

The first set of (round capped) nuts wasn't galvanised and started rusting (you can see it in the photos). Haven't been able to find galvanised ones for the imperial bolts, so I've since replaced them with galvanised normal nuts.

Pros and Cons

It's freaking awesome! Having a shady spot next to the car wherever you roll up is great!

The awning is big. Not much of an issue once it's mounted but it's pretty unwieldy in the garage.

The surface area covered is perfect for two people and a table, so no issues there.

The awning is not free-standing. I believe the commercial models are, but this one needs to be pegged down. Which means that moving the car once it's set up is a no-go, you have to tear it down.

The way I roll it results in rain collecting in the rolled-up tarp. I could roll it the other way, but that's a bit awkward. No big issue though, except after a good rain when you break at the first set of lights, a few litres of water will run down your windscreen :)

I can't yet claim how it will hold up in a typical Queensland wind or thunderstorm. I think it will be alright, but so far I've only had it up during light winds and light rain.

Really impressed with you're design. I didn't have a piece of aluminum at home, so used a 25x25 hardwood as the rail to attach the trap to. I used a 2.4m by 3m HD trap and used poles like you did and it worked a dream. Well up really well during reasonable wind and rain. Was really impressed with how strong it was. I had a roof rack similar to yours and i just used washers with a nut welded to one side that slip into the groove on the roof rack.